The widgets in the “Forms” section of the default Axure library all use browser-defined styling. Each browser will render them differently, and this is a “2 sides of the coin” thing–sometimes good, sometimes bad. RP9 introduced a few overrides for some of these widgets, but none can be “fully styled.” So, you are left to build it yourself manually if you want full control of visuals.
You can also browse the available Axure Libraries to see if a pre-built version can work for your needs, or search this forum for examples, like these: